The present invention relates to ski bindings and more particularly to a method and apparatus for initiating release within the bindings in order to prevent or minimize injuries, especially in the lower extremities of the skier.
In the past, a wide variety of ski bindings has been developed and made commercially available in view of the greatly increasing popularity of snow skiing. Along with the increase in popularity and practice of snow skiing, there has been a corresponding increase in injuries, especially in the lower extremities of the skiers. Generally, ski injuries have tended to concentrate in the tibia, in the form of mid-length fracture, as well as in the ankle and knee.
There has been a substantial effort to improve all types of ski equipment for minimizing such injuries including improvements in ski boots and skis themselves as well as in ski bindings. However, much effort directed toward the elimination or prevention of such injuries has concerned the binding since it has been found that release of the skier from the ski is one of the most effective means of protecting the skier during injury-provoking situations such as falls and the like.
Until approximately 1973, commercially available ski bindings were designed and adjusted for mechanically initiating release by limiting the magnitude of loading between the boot and ski. This design approach is generally based upon the theory that deformations, particularly in components of lower extremities of the skier, are directly related to loading magnitude. However, it came to be realized that bindings designed according to this theory did not satisfy the dual requirements of safety and retention. In this connection, safety requires that the binding release the skier in sufficient time to prevent predictable injury. However, because of a failure to accurately predict such injury-provoking situations, bindings adjusted for such safety considerations have often tended to be subject to premature release during skiing, even under conditions appearing unlikely to produce injury. On the other hand, with bindings being adjusted to assure retention under different skiing conditions, there has been found to be a greater tendency for injury.
Accordingly, there has developed another theory for injury prevention during skiing based on the recognition of a dynamic system of the lower skier extremities as a biomechanical system consisting of inertia, stiffness and dissipative elements. It was hypothesized that under loading conditions typical in skiing, such a system is excited dynamically with no direct relationship between applied loading magnitude and deformation. This hypothesis was confirmed by actual tests and measurements indicating that the frequency content of lower extremity loading was sufficient to excite the dynamic model. In order to explain the inability of ski bindings to simultaneously satisfy safety and retention requirements, it was further hypothesized that binding release levels were not sufficiently sensitive to load duration. Accordingly, further experimental studies were conducted for binding release levels under shock loading in order to confirm this hypothesis, whereupon a general conclusion has developed that such a dynamic system theory of lower extremity injury is able to simultaneously satisfy both release and retention requirements.
However, it has been found that ski bindings presently available do not take advantage of this theory or otherwise fail to include suitable techniques or apparatus for initiating release within a binding in order to realize the potential advantages of such a dynamic system.